Pilot Scale Extraction and Fractionation of Rice Bran Oil Using Supercritical Carbon Dioxide

Abstract

In the first stage of this two-stage process, crude rice bran oil was extracted with supercritical carbon dioxide (SC-CO2) from a 300 g batch of rice bran. Oil-laden SC-CO2 from the extractor (24.1 MPa/40 °C) passed continuously to a second-stage column where an oil phase (raffinate) separated from the SC-CO2 at various controlled temperatures and pressures. Measurement of the compositions of raffinates and extracts allowed calculation of partition coefficients of triglycerides, free fatty acids (FFAs), α-tocopherol, sterols, and oryzanol and, hence, the selectivities of the fractionations. Fractionation removed almost all water and reduced the FFA concentration in raffinate by up to 50%. Oryzanol and α-tocopherol concentrations in the raffinate were not reduced by fractionation, but the sterol concentration was reduced under conditions favoring FFA removal. Under the flow rate conditions studied (3.5 kg of CO2/h), the fractionations could be described by equilibria between oil and CO2 phases. Keywords: Supercritical carbon dioxide; extraction; fractionation; rice bran oil